SOLUTION: The diamerter of the Mily Way disc is approximately 9 x 10^20 meters. How long does it take light, traveling in 10^16 m/year to travel across the diamerter of the Milky Way? I a

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Question 70805This question is from textbook Beginning Algebra
: The diamerter of the Mily Way disc is approximately 9 x 10^20 meters. How long does it take light, traveling in 10^16 m/year to travel across the diamerter of the Milky Way?
I am really confused on this one, and need some help.
Thanks This question is from textbook Beginning Algebra

Found 2 solutions by josmiceli, jim_thompson5910:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
This is just distance/rate = time
meters / m/yr
%289+%2A+10%5E20%29%2F+10%5E16 = time in years
9%2A10%5E4 years
or 90,000 years

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Look at this as a rate problem, but with much larger numbers. Use the equation d=rt. Let d=9 x 10^20 meters (diameter of galaxy) and r=10^16 m/year (speed of light in meters per year).
Solve for t by dividing both sides by 10^16 m/yr
Divide the numbers by subtracting exponents. Remember similar units cancel
t+=+9+x+10%5E4+%2A%28yr%29
So it takes 9 x 10^4 *(yr) or 90,000 yrs for light to go across the diameter of the Milkyway.